Onne
Part of things
Posts: 822
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Hello all,
As you may know I run a 300SE on LPG. The car still starts on petrol.
As of late she takes more and more cranking to get going, but not consistently (sometimes she'll fire straight up)
Spark is lovely and fat, good compression.
So the real question here is, how do I test my fuel supply, what pressure should it be etc. When I bought the car it had a leaky fuel pump, which I replaced with Ebays finest.
Can that ruddy pump be on its way out already? It's a hateful thing to replace...
Cheers!
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Last Edit: Dec 9, 2011 14:48:45 GMT by Onne
1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Onne
Part of things
Posts: 822
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Dec 10, 2011 21:31:23 GMT
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Anyone any ideas or shall I just go for a new pump? I'm not a fan of the just replace method...
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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bortaf
Posted a lot
Posts: 4,549
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Dec 10, 2011 21:47:59 GMT
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IME EFi pumps either work or they don't ? fuel pressure will beemeasured at the fuel rail, there will be a schrader valve somewhere on it (tyre valve) it could be the fuel pressure reg sticking but that's not something i've found happens all that oftem more likely (IF it has it) is the vac advance is sticking in the dizzy (but most EFi cars don't have a vac advance the ECU does it all), i would check whatever the LPG uses to shut of the petrol, there maybe a valve or solenoid sticking somewhere? sDoes teh car run a seperate LPG ECU? TBH diagnosing from a distance is hard enough but not knowing what system you have or the type makes it harder still hense the lack of replys  |
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R.I.P photobucket
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Onne
Part of things
Posts: 822
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Dec 10, 2011 21:59:16 GMT
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It's K-Jetronic (so Bosch) LPG is run completely separately.it tries to start up straight away but it is as if the fuel pressure drops (turn key, fires straight up but doesn't seem to have enough fuel to keep going)
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Dec 10, 2011 23:10:01 GMT
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Doesnt a K-jet have a vacuum operated fuel pressue accumulator or something next to the pump?
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Onne
Part of things
Posts: 822
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Yes it does... And I did fart around with the vacuum pipe to it. The original pipe broke when I removed it, I replaced it with a piece of copper pipe. Can I test the accumulator?
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Dec 11, 2011 10:37:42 GMT
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I would assume it would just have a diaphram in, so as long as it holds a vacuum it should be working ok. don't quote me on any of this though.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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